Abstract
The second-order rate
constants and activation parameters for the addition of 1,10-phenanthroline to bis(dialkyldithiophosphato)nickel(II) complexes and substituted
bis(monothioacetylacetonato)-nickel(II) complexes in
toluene have been measured. Rate constants are in the range 102-108
1. mol-1 s-1 at 25°C, while ΔH‡ is in the
range 10-50 kJ mol-1 and ΔS‡ is in the range from
-30 to -110 J mol-1 K-1. The higher rate constants,
smaller ΔH‡ and more negative ΔS‡ values are associated
with complexes with electron- withdrawing substituents. The results are related
to the thermo- dynamics of adduct formation, the inductive effects of the
substituents and the pKa of the ligands.